Contributions
Abstract: 131
Type: Oral
When probing the effects of new drugs aiming at such a mode of action, e.g. in the context of phase II treatment trials, in vivo imaging markers of neuroprotection and repair in MS are needed. In this context, the Magnetization Transfer Ratio (MTR) obtained by Magnetization Transfer (MT) Imaging appears as an attractive candidate. The MT contrast is based on the exchange of magnetization between immobile macromolecular protons and mobile tissue water and therefore allows to depict otherwise invisible protons. The efficacy of transferring the magnetization may be quantified by the MTR, a measure that can be obtained from two separate measurements, where one measurement is combined with a saturation of macromolecular protons. The MTR is quantitative, reproducible, and comparable among subjects, provided the same scanner and sequences are used and has been applied successfully in multicenter studies. Due to its relative simplicity, it is also more frequently used than a true quantitative MT analysis. In brain tissue, the MTR correlates with macromolecular density. It is therefore thought to reflect myelin. Supportive evidence for this concept comes from basic models of MT and histopathological MRI-correlation studies. Importantly, an increase of MTR has been proposed as a putative marker of remyelination with moderate pathologic specificity, good reproducibility and good sensitivity to change. This presentation will therefore critically discuss the strengths and limitations of this approach including newer developments, and try to highlight obstacles to more widespread use of this technique.
Disclosure: The author declares no conflict of interest with regard to this presentation.
Abstract: 131
Type: Oral
When probing the effects of new drugs aiming at such a mode of action, e.g. in the context of phase II treatment trials, in vivo imaging markers of neuroprotection and repair in MS are needed. In this context, the Magnetization Transfer Ratio (MTR) obtained by Magnetization Transfer (MT) Imaging appears as an attractive candidate. The MT contrast is based on the exchange of magnetization between immobile macromolecular protons and mobile tissue water and therefore allows to depict otherwise invisible protons. The efficacy of transferring the magnetization may be quantified by the MTR, a measure that can be obtained from two separate measurements, where one measurement is combined with a saturation of macromolecular protons. The MTR is quantitative, reproducible, and comparable among subjects, provided the same scanner and sequences are used and has been applied successfully in multicenter studies. Due to its relative simplicity, it is also more frequently used than a true quantitative MT analysis. In brain tissue, the MTR correlates with macromolecular density. It is therefore thought to reflect myelin. Supportive evidence for this concept comes from basic models of MT and histopathological MRI-correlation studies. Importantly, an increase of MTR has been proposed as a putative marker of remyelination with moderate pathologic specificity, good reproducibility and good sensitivity to change. This presentation will therefore critically discuss the strengths and limitations of this approach including newer developments, and try to highlight obstacles to more widespread use of this technique.
Disclosure: The author declares no conflict of interest with regard to this presentation.